Insect pests cause heavy losses to stored grain, quantitatively and qualitatively (Sinha R. N. and Watters F. L. (1985), Insect Pests of Flour Mills, Grain Elevators, and Feed Mills and Their Control, Agriculture Canada, Publication 1776, p. 290; Madrid F. J., et al (1990), Can. Ent. 122, 515-523). Synthetic residual insecticides and fumigation are the main method of grain protection. However, increased public concern on the residual toxicity of insecticides applied to stored grain and the occurrence of insecticide-resistant insect strains are causing people to search for alternative methods to control insect pests.
It has long been known that legume seeds contain a wide range of chemicals with toxic or deterrent effects against insect pests (Harborne J. B., et al (1971), In Chemotaxonomy of the Leguminosae, Academic Press, London. p. 612; Bell E. A. (1978), Toxins in seeds, In Biochemical Aspects of Plant and Animal Coevolution, (Edited by Harborne J. B.) pp. 143-161, Academic Press, New York. p.435). The most common of these insect-active substances in the seeds of legumes are protease inhibitors (eg. the now classical soybean trypsin inhibitor), lectins of various specificities and a broad range of saponins. None of these substances, however, has been adapted commercially for controlling insects infesting grain. An admixture of yellow split-peas (Pisum sativum) with wheat resulted in a marked reduction of survival and reproduction of the rice weevil (Sitopulus oryzae) (Coombs C. W., et al (1977) J. Stored Prod. Res. 13, 53-58; Holloway G. J. (1986) Bull. ent. Res. 76, 287-295). These effects were achieved, however with admixtures containing equal weights of whole peas and wheat, and the method is not practical for controlling pests in grain that is being transported or stored.
Insect pests also cause heavy losses in various agricultural crops, including but not limited to canola and wheat.
There is thus a need to identify a component or fraction within a pea extract that can act as a natural insecticide against insects.